1. Field of the Invention
The present invention relates to a radiation apparatus comprising a radiation source and a filter which is disposed in an optical path and comprises two transparent discs which are arranged substantially in plane-parallel fashion to each other and which are held with their surrounding edges in a frame made of a material of good heat conduction, the discs and the frame defining a closed cavity which has provided therein a medium for selectively influencing the radiation spectrum.
2. Description of the Related Art
Such a radiation apparatus is, for instance, known from EP-A-0311898. The radiation apparatus described in the publication is used for heat therapy, especially of the human body. The purpose of the filter used in this apparatus is that the radiation spectrum in its entirety as emitted by the radiation source is suited for heat therapy to a limited degree. That is why specific bands of the radiation spectrum are filtered out by the filter. The known filter consists of a multipart frame which is composed of an outer frame connected to the housing of the radiation apparatus and of an alternate frame which is arranged therein and carries both filter discs. Two press rings are arranged on the alternate frame for pressing the two filter discs each in tho direction of the cavity onto their seals. At least one of the press rings is undetachably connected to the alternate frame by way of a flanging operation.
It is the object of the present invention to improve a radiation apparatus of the above-mentioned type in such a manner that the structure of the filter becomes more simple.